Cisplatin is an effective antineoplastic drug for the treatment of solid tumors, although its clinical use can be limited by adverse effects on renal function. This side effect often delays or precludes subsequent chemotherapy cycles, thereby reducing the overall antineoplastic efficacy of cisplatin, Preliminary data demonstrate that mice lacking the renal drug transporter Mrp2 have an increased susceptibility to cisplatin nephrotoxicity. In addition, Mrp2 is Induced in the kidneys of cisplatln-treated wild-type mice likely as a compensatory mechanism to enhance clearance of subsequent chemotherapy cycles. Experiments in this proposal will test the hypothesis that Mrp2 is critical for the disposition of cisplatin and prevention of cisplatin nephrotoxicity. Furthermore, it is hypothesized that the inducible expression of Mrp2 is regulated by the oxidative stress-responsive transcription factor Nrf2. In Specific Aim 1, we will determine the in vivo contribution of Mrp2 to the renal disposition and toxicity of cisplatin using Mrp2-null mice. In Specific Aim 2, we will establish which single nucleotide polymorphisms in human MRP2 influence transport of cisplatin conjugates and cisplatin cytotoxicity using an in vitro overexpression system. In Specific Aim 3, we will determine the role of Nrf2 in the compensatory induction of Mrp2 during cisplatin injury using Nrf2-null mice and in vitro ChlP assays. The work proposed in this grant serves as the independent portion of the K99/R00 grant. The proposed studies are expected to reveal the role of Mrp2 transport In protecting the kidneys from cisplatin toxicity.